Originally Posted by sanking
I never meant that making a high quality carbon print is going to be a cake walk, rather with pre-made tissue the physical actions one performs isn't that demanding procedurally. Quoting from your chapter in Barnier's book on page 89, "...the carbon process is a rather straightforward operation that, once learned, offers a range of possibilities not available with any other photographic system."; this seems to be the essence of my initial experience.
However after reading your extended article found on the View Camera web site there are some procedural differences when compared to the instructions provided by Bostick & Sullivan.
First is the method of sensitizing the tissue. In your extended notes for tray sensitization you specify using only water for the dichromate solution. The B&S instructions specify acetone or isopropyl alcohol to be used for 50% of the solution volume. In contrast you recommend using a spirit sensitizer for brush sensitizing. Personally I would rather not use a spirit based method of sensitization.
Second, your article has much more specific details about what dilution of dichromate to use for various negative DRs. Specifically you wrote, 'In working with the B&S carbon tissues it will be found that the practical effective range of a postassium dichromate sensitizer varies from a low of about 1% up to a high of around 3%.' However in your curve illustrations you show plots for dichromate solutions that range from .25% to 2%. I'm not sure what practical conclusions to make of that. In other words can .25% really be used with the B&S tissue or is 1% the bottom limit? Or are you simply making the point that a .25% dichromate dilution will produce an incredibly slow tissue? The B&S instructions specify a .5% dilution for a 'silver style' negative. Whatever the real limitation may be I'll measure the DR of my negative to see if I can practically make a decent print with it. Unfortunately it is a pyro (PMK) stained negative and I don't have a UV densitometer to measure the effective DR.
Third, it is interesting to note from your article that the ES of the printing process is determined by the combination of tissue/sensitizer. I can understand that, but isn't the final contrast of the print also influenced by the receiver paper (at least to a small degree).
Fourth, the B&S instructions suggest that the tissue and transfer paper be mated for about 10 minutes before development begins, you on the other hand specify 30 minutes. Perhaps you touched on this in the publically published version in View Camera, unfortunately my copy isn't handy so I can't compare. What effect does the RH and ambient temperature have on the transfer?
Fifth, its not clear to me from reading the B&S instructions and your extended article what is the proper lenght of time for presoaking the receiver paper. In your chapter 'Monochrome Carbon', for Barnier's "Coming Into Focus" you suggest a 15 minute cool water presoak. In fact the B&S instructions don't specify a time. Unfortuantely I presoaked for perhaps 1 or 2 minutes. Vaughn Hutchins suggests a cool water pre-soak for as long as 6 hours, that seems a little nonsensical and extreme.
Sandy, I hope you don't mind all of the questions, I'm hoping others will benefit from this discussion too.